Spar buoy vessel



Dec. 3, 1968 H. u. VON SCHULTZ 3,413,946

SPAR BUOY VESS EL Filed Aug. 31, 1966 2 Sheets-Sheet 1 68 mvsm'onA'ITORNEY Dec. 3, 1968 H. u. VON SCHULTZ 3,413,946

SPAR BUOY VESSEL Filed Aug. 31, 1966 2 Sheets-Sheet 2 INVENTORA'FI'ORNEY HANS UDO VON SCHULTZ United States Patent 3,413,946 SPAR BUOYVESSEL Hans Udo von Schultz, Fort Worth, Tex., assignor to Mobil OilCorporation, a corporation of New York Filed Aug. 31, 1966, Ser. No.576,338 31 Claims. (Cl. 114-.5)

ABSTRACT OF THE DISCLOSURE This specification discloses a versatilefloating vessel suitable for the exploitation of subaqueous fluidmineral deposits. The vessel includes a shipshaped platform and a sparbuoy hull connected so that the vessel can be transported across a bodyof water with the portions thereof aligned to form a compositeshipshaped vessel. The vessel is arranged at a marine site with the sparbuoy hull depending vertically into the water and supporting theplatform above the surface. The platform maintains the same orientationin both arrangements. With 'a drilling rig mounted on a deck of theplatform, a drill string can be guided into a borehole extending intothe formations underlying the marine bottom through a passage extendingthrough the spar buoy hull of the vessel. The spar buoy hull can beutilized as a portion of a marine conductor pipe. The vessel can bedynamically positioned, the positioning motors being controlled inconjunction with transponders fixed on the marine bottom around theborehole, or means for detecting the deviation of the drill string fromthe axis of the passage through the spar buoy hull in which it issuspended.

This invention relates to a versatile marine structure for providing astable above-surface platform at a marine site. More particularly, theinvention relates to a spar buoy drilling vessel that can be transportedacross a body of water at relatively high speeds.

When drilling in deep water, especially depths beyond that which may nowbe reached with a bottom-supported template or a jack-up platform, thefloating drilling vessel has found acceptability. Of the variousconfigurations of floating drilling vessels, the spar buoy type istheoretically the most stable under many conditions and therefore wouldbe desirable, particularly in areas noted for frequent storms. A sparbuoy type of drilling vessel, however, would be an extremely unwieldystructure and, as of this date, none have been built. In fact, the onlyspar buoy type vessel that is known to exist at this time is anexperimental flip-ship (Flip Floating Instrument Platform, Journal ofAcoustical Society of America, vol. 35, No. 10, October 1963) beingutilized for oceanographic work. The flip-ship has overcome one of themajor drawbacks of the spar buoy type of marine vessel by its uniqueconstruction which allows it to be reoriented from a position in whichit can be transported, horizontally On the surface of a body of water,to a stable working position at a marine site, depending vertically intothe body of water. However, while such a vessel may be very useful as aresearch instrument, it would not be accept-able in the oil and gasindustry, as a drilling vessel, due to the reorientation of the entirevessel including the working decks.

Exploration and production efforts in the oil and/or gas industry havebeen extended to remote areas throughout the world subsequent to theleasing of the more accessible and desirable acreages. In the recentdrive to discover and tap hydrocarbon deposits beneath the continentalshelves and even the more recent developing ability to extend theexploitable regions to the deeper waters of the continental slopes (over600 feet), leases have been obtained for such remote offshore areas asthe West Coast of Africa and the coasts of Australia. In some of thePatented Dec. 3, 1968 largely untested areas, leases may be obtained foronly one or two hundred dollars an acre, resulting in very large tracts.To make the use of a spar buoy type of drilling vessel practical, itmust be possible to transport the vessel quickly from its home port tothe above-discussed remote areas, at which it will be located duringdrilling operations and it must be furthermore possible to quickly andeasily move the vessel from one exploratory drilling site to anotheracross a large tract. Even a conventional drilling platform of thejack-11p or wave transparent types, under tow from the United States tothe remote foreign site and back, expends ninety to two hundred days atthe usual towing speed of two to three knots. The cost of transportingso immense a structure across the span of an ocean includes towingcharges of $1,000 to $1,500 per day, plus towing insurance of $400 to$500 per day in addition to a per diem rate. (The quoted charges aremerely representative and are only included to permit the reader toobtain an appreciation of the magnitude of the costs involved in theoperation of a marine drilling veS- sel.)

The optimum drilling vessel, when considering only the speed at which itcan move across a span of water, is one of shipshaped design. Examplesof such vessels are the Glomar and the Torry, that have been usedextensively for drilling in the coastal waters of the United States.These vessels are similar to an ordinary ocean-going freighter with theexception of a moonpool or central vertical well which is formed throughthe hull of the vessel directly below the drilling rig. The problem witha shipshaped drilling vessel is that it is greatly affected by anysurface winds and wave action. Drilling operations must be suspendedduring rough weather and the vessel must be completely removed from thedrilling site during storms. While heave, pitch, roll, and the otherpossible motions occurring on a vessel at sea may be compensated for, tosome degree, during the drilling operation, there is an acceptable levelof motion above which the drilling or workover operations must beterminated. For example, with shipshaped vessels in the Gulf of Mexicoin 1964, over five percent down time was experienced by contractors dueto weather conditions alone.

A spar buoy type of drilling vessel, however, can remain at a site andcontinue drilling through all but the most violent storms. Due to thedepth at which the spar hull depends beneath the waters surface, thedeck motions resulting from surface agitation are greatly subdued to thepoint at which they are no longer a major problem. However, this type ofdrilling vessel with its supporting spar buoy hull, depending deep intothe water, causes a tremendous hydrodynamic drag during towing. Most ofthe suggestions to date, on using a spar buoy type of drilling vessel,have considered using a prefabricated structure which is assembled atthe site and then must be disassembled and removed by barge to the nextdrilling site. Such an undertaking is not feasible in remote areas wherefacilities for such operations are extremely limited.

Accordingly, it is an aspect of the present invention to provide astable marine platform structure capable of drilling and maintainingsubaqueous wells in deep water.

It is another aspect of the present invention to provide a stable marineplatform or structure capable of being towed, or propelling itself, longdistances at speeds substantially equal to those of a shipshaped vessel.

Other aspects and advantages of the present invention will be readilyapparent from the following description, when taken in conjunction withthe accompanying drawings which illustrate useful embodiments inaccordance with this invention:

FIGURE 1 is an elevational view of the marine drilling vessel of thepresent invention showing the spar buoy hull thereof floating in ahorizontal position on the surface of the body of water behind theshipshaped hull of a working platform, when the marine drilling vesselis under tow or being self-propelled to a remote site;

FIGURE 2 is an elevational view, partially in section, of the marinedrilling vessel of FIGURE 1, with the spar buoy hull thereof floatingvertically in the body of water to support the working platform abovethe surface during a drilling or workover operation, and illustratingmeans for determining when the floating marine drilling vessel hasdrifted away from a position directly above a subaqueous borehole;

FIGURE 3 is a cross-sectional view taken along line 33 of FIGURE 2illustrating the means for adjusting the orientation of the spar buoyhull with respect to the above-surface platform;

FIGURE 4 is a view taken through line 4-4 FIG- URE 2 illustrating, inschematic form, a photoelectric position indicating system;

FIGURE 5 is an illustrative view of the face of a receiving instrument,partially broken away, that would be mounted on the bridge or in thecontrol room on the marine drilling vessel for visually showing anoff-center position of the drill string as recorded by the photoelectricposition indicating system of FIGURE 4;

FIGURE 6 is an elevational view, partially in section, of the marinedrilling vessel of the present invention, modified so as to function asa portion of a marine riser extending from above the surface of the bodyof water to the marine bottom where it is connected with the subseawellhead of a subaqueous well; and

FIGURE 7 is a cross-sectional view of the lower end of the spar buoyhull as shown in FIGURE 6 illustrating the means for suspending asection of marine riser pipe in the lower end of the spar buoy hull.

The invention comprises a floating drilling vessel consisting of ashipshaped platform attached by a pivotable arrangement to alongitudinally elongated spar buoy hull and means for adjusting theorientation of the spar buoy hull with respect to the platform, wherebythe longitudinal dimension of the spar buoy hull is vertically orientedso as to depend deep into the water during drilling, and floats with itslongitudinal dimension horizontally oriented along the surface of thewater, behind the shipshaped platform to form a composite shipshapedvessel, when it is being transported, the deck of the platform remaininghorizontal in all positions of the spar buoy hull.

Now looking to FIGURES 1 and 2, the marine drilling vessel, generallydesignated 10, consists of a spar buoy hull .12 and a shipshapedplatform 14. The platform 14 is pivotally connected to the upper end ofthe spar buoy hull 12, being suspended between a pair of spaced arms 18of a bifurcated section or yoke 16. The platform 14 has a shipshapedhull 19 and an above-surface working deck 20 with a drilling rig 21mounted thereon above a central drilling well or moonpool (not shown)while the spar buoy hull 12 is an elongated cylindrical column having acentral vertical well 22 coaxial with and beneath the moonpool of theshipshaped platform 14 when the vessel is in the position shown inFIGURE 2. An annulus 24, between the wall of the central well 22 and theouter wall of the spar buoy 12, is longitudinally compartmented bybulkheads 26 to form watertight compartments 27 that can be separatelyand controllably flooded to function as buoyancy/ ballast tanks.

In FIGURE 1, the marine drilling vessel 10 is shown as it would bepositioned when moving toward a remote marine site. The shipshapedplatform 14 and the spar buoy hull 12 are both floating on the surface28 of a body of water 30 and may be locked in position with respect toeach other by means which will be later described. When the marinedrilling vessel -10 is in the position shown in this view, thelongitudinal dimension of the hull 19 of the platform is parallel to thelongitudinal dimension of the spar buoy hull 12 forming a substantiallshipshaped sea-going vessel capable of traversing an ocean at about thespeed of a large tanker.

As shown in FIGURE 2, the spar buoy hull 12 is floating verticallySuspended in the body of water 30 with the platform 14 located at adesired distance above the surface 28 supported by the connectingsection or yoke 16. A drill string 32, suspended from the drill rig 21on the platform 14, extends through the central well 22 of the spar buoy12 and into a marine bottom 34. While the marine drilling vessel 10 isin the position shown in FIGURE 2, the platform 14 is locked againstmovement relative to the spar buoy hull 12 to prevent any tilting of theplatform 14 due to the shifting of equipment on the decks thereof.

In FIGURE 3 is illustrated a portion of one of the arms 18 incorporatinga means for selectively rigidly fixing or locking the platform 14 withrespect to the spar buoy hull .12. The upper end of the representativearm 18 has a cylindrical aperture 36 in the inwardly facing surfacethereof. The opposing arm 18 has a coaxial cylindrical aperture 36 inthe inwardly facing surface thereof. Fixed to the opposite sides of theshipshaped hull 19 of the platform 14 are large backing plates 38, eachcarrying a circular pattern, or configuration, of roller bearings 40,the roller bearings 40 being journaled on stub shafts 42 extendingperpendicularly from the outer faces of the backing plates 38, and intothe interior of the apertures 36 in the corresponding arms 18 so thatthe roller bearings 40 bear on the inner wall of the apertures 36 forpivotally mounting the platform 14 between the arms 18 of the connectingsection or yoke 16. A pair of pivotal brake shoes 44 is coaxiallyjournaled on a shaft 46 fixed to the outer face of each backing plate 38radially inward of the circular configuration of roller bearings 40 andis designed to coact with an annular drum 48 concentrically mounted, oneach of the arms 18, within the interior of the respective aperture 36.A circular internal rack 50 is fixed to the inner wall of the annulardrum 48 and meshes with a pinion 52 mounted on a shaft 54 journaledthrough the backing plate 38 and driven by a motor (not shown) on theabove-surface deck 20 of the platform 14. Shafts 56, also journaledthrough the backing plates 38, and driven from a motor (not shown)mounted on the deck 20 of the platform 14, each have a reel 58 fixed onthe outer end thereof exterior of the backing plates 38. Pairs of cables60 are interconnected between each of the reels 58 and each pair ofbrake shoes 44 such that when the reels 58 are rotated in one direction,the pairs of brake shoes 44 are clamped tightly against the annulardrums 48 and when the reels 58 are rotated in the opposite direction, apredetermined distance, the pairs of brake shoes 44 are released fromcoacting with the drums 48.

When the marine drilling vessel 10 is in either of the positions shownin FIGURES 1 or 2, the pairs of brake shoes 44 are held tightly againstthe drums 48 to prevent any relative movement of the platform 14 withrespect to the spar buoy hull 12. When the vessel 10 is to be reorientedfrom one of the illustrated positions to the other, the brake shoes 44are deactivated by rotating the drum 48 and the change of position ismade by adjusting the buoyancy in the various compartments 27 of thespar buoy hull 12. The gear sets, consisting of the pinions 52 and theinternal racks 50, provide a fine adjustment of the relative position ofthe platform 14 with respect to the spar buoy hull 12. After the finaladjustments have been made, the reel 58 is counter-rotated tore-establish contact between the brake shoes 44 and the annular drum 48to lock two sections of the marine vessel 10 together.

In reorienting the spar buoy hull 12 from the position shown in FIGURE 1to the position shown in FIGURE 2, enough compartments 27 should beflooded to obtain a negative buoyancy, submerging completely the sparbuoy hull 12 and allowing it to hang suspended from the then supportingfloating platform 14. Once the spar buoy hull 12 has attained thevertical orientation shown in FIGURE 2 and the position of the spar buoyhull 12 has been finely adjusted with respect to the platform 14, andthe spar buoy hull 12 is locked in place with respect to the platform14, some of the compartments 27 are blown free of water, by compressedair, causing the spar buoy hull 12 to rise partly out of the body ofwater 30 and support the platform 14 above the surface 28 as shown inFIGURE 2. The buoyancy/ballast tanks in the spar buoy hull 12 shouldhave a capacity sufiicient to support the platform 14 forty feet or moreabove the surface 28 where it is relatively isolated from the surfacewaves. The reverse procedure would be followed for bringing the drillingvessel back to the position shown in FIGURE 1.

Although bottom anchoring systems have been successfully devised fordeep water floating drilling operations, it is expected that a marinevessel such as the spar buoy type of the present invention would, infact, be dynamically positioned. For this purpose an upper ring ofpropeller driving propulsion motors 62, and a lower ring of propellerdriving propulsion motors 64, are fixed to the spar buoy hull 12. Thesemotors 62 and 64, in combination, can control the drift of the marinedrilling vessel 10 as well as its attitude in the body of water 30.

In FIGURE 2, alternative techniques for locating the marine drillingvessel 10 over a subaqueous borehole 66 are illustrated. One method oflocating the vessel 10 over a marine site is by placing a plurality ofacoustic transponders 68 on the marine bottom 34, in a pattern around.the borehole 66, and mounting corresponding acoustical transducers 70 onthe lower end of the spar buoy hull 12 for receiving signals therefrom.Each of the transducers 70 may be keyed to respond to a single one ofthe transponders 68 so as to provide not only an indication of lateralpositioning but also of radial positioning. Another method of locatingthe vessel 10 over a site utilizes the displacement of the drill string32 in the lower end of the spar buoy hull 12, the drill string 32 beingsuspended from the drilling rig 21 on the above-surface deck 28 of theplatform 14 and extending through the well 22 of the spar buoy hull 12and into a borehole 66 in the marine bottom. An off-center position ofthe drill string 32 in the central well is an indication of acorresponding deviation of the vessel 10 from directly over the boreholein the marine bottom 34. A position indicating means consisting of aphotoelectric position sensing means, generally designated 72, locatedat an observation area within the lower end of the cylindrical well 22,shown in detail in FIGURE 4, has two banks of photocells 74 and 76mounted at 90 relative to each other around the circumference of thewell 22 and at different axial levels. A bank of light sources 78, 80 ismounted diametrically across the well 22 from each bank ofphotosensitive devices 74 and 76, respectively. Each light source 78, 80consists of a tubular compartment 82 having an open end facing the well22 of the spar buoy hull 12. Within each compartment is a light bulb 84and a focusing lens 86. A transparent plate 88 seals the open end ofeach of the tubular compartments 82 which opens into the central well22. The light emitted from the bulb 84 at a source 78 is focused throughthe respective lens 86 into a narrow beam of light 90 to impinge on acorresponding photocell 74 diametrically opposite. In a similar manner,a beam of light 91 originating in a source 80 is focused to impinge onthe corresponding photocell 76. The light beams 90, 91 of each bank 78,80, respectively, are preferably parallel to form -a uniform grid;however, the beams 90, 91 of the two parallel banks 78, 80 can cross atany convenient angle. Normally 90 is the most convenient arrangement.

The light bulbs 84 of both banks may be individually grounded (notshown) and wired in parallel to a single power source 92 here shown as abattery 93. The electric voltage generated in the photocells 74 and 76,corresponding to the light impinged thereon from the light sources 78and 80, is amplified by individual amplifiers 94 and energizes throughrespective wires 96 the corresponding light bulbs in a visual displayinstrument 98 (FIGURE 5) that would be mounted on the deck 20 of theplatform 14 where it could be observed by an operator who could in turncontrol the propulsion motors 62 and 64 to bring the marine drillingvessel 10 back over the borehole 66.

The display instrument 98 consists of two banks of parallel transparentlight conducting elements such as glass or Lucite rods 100 and 101extending across the instrument 98 beneath the circular transparent facethereof, the banks of parallel rods being perpendicular to each other toform a grid arrangement which corresponds to the light beams 90 and 91,respectively, of the position sensing means 72 of FIGURE 4. A separatelight bulb 102 is mounted in a shielding case 103 adjacent an end ofeach of the rods 100 and 101. The light bulbs 102, associated with eachof the rods 100 and 101, are electrically connected, through amplifiers94, to the photocells 74 and 76, respectively. When the central passage22 is empty, all of the rods 100 and 101 in the display instrument 98are illuminated. The beams of light 90 and 91, emitted by the lightsources 78 and 80, impinge on the photocells 74 and 76, creating anelectrical potential in each of the photocells. An electric current iscreated in each circuit containing the light bulbs 102, activating thebulbs and illuminating the respective rods 100 and 101. When a drillstring is suspended in the passage 22, all of the rods are illuminatedexcept for one rod 100 and one rod 101. A beam of light 90, emitted by alight source 78 is blocked by the drill string 32 before it can reachthe opposing photocell 74, and therefore no electrical potential isgenerated in the photocell 74. The light bulb 102, associated with therod 100' in the display instrument 98, is not activated and the interiorof the glass rod 100' is not illuminated. The beam of light 91' emittedby a light source is also blocked by the drill string 32 before it canreach the photocell 76 and therefore the light bulb 102, associated withthe rod 101 is not activated and the interior of the glass rod 101' isnot illuminated. The point of intersection 104 of the unlighted glassrods 100 and 101' corresponds to the position of the drill string 32 orany other object in the lower end of the central well 22. This positionwould in turn vary as the position of the vessel 10 with respect to theborehole 66. In the previously described arrangement, the display rods100' and 101 are not lighted, forming a dark pattern in contrast withthe lighted surrounding rods. It is possible to design the inversearrangement where the rods 100 and 101, corresponding to the interruptedbeams and 91', are the rods that are lighted to contrast with theunlighted surrounding rods and 101. It is well within the skill of theart to provide a system for automatically controlling the propulsionmotors 62 and 64 from either of the position indicating means described.

An open drill string 32, extending from the platform 14 directly to theborehole 66, shown in FIGURE 2, would be acceptable if coring operationswere being conducted where water could be used as the drillingcirculation fluid. While such operations may be successfully conducted afew hundred feet into the underlying formations, water is not heavyenough to prevent blowouts, and for drilling a wildcat or productionwell provision must be made for returning the heavy drilling mud,injected into the borehole 66 through the drill string 32, to the deck20 of the plat-form 14. One method of returning the mud when using anopen drill string would be by utilizing a submerged drilling wellheadsystem of the type described in the R. F. Bauer et a1. Patent No.2,808,229, issued Oct. 1, 1957, in which the drilling mud is conductedback to the surface vessel from a point adjacent the marine bottom by aflexible line. However, it has been found to be more satisfactory toprovide a marine riser pipe between a subsea wellhead and a surfacevessel to guide the drill string between the vessel and the wellhead andfor the annulus thereof to act as a return conduit for the drilling mud.

In FIGURE 6, there is shown a method for connecting the platform 14 ofthe drilling vessel with a subsea borehole 66 by using the central well22 of the spar buoy hull 12 as a portion of a marine riser. A section ofmarine riser pipe 106 is suspended in the lower end of the central well22 and depends to the subsea wellhead 108 and a blowout preventer stack110 capping the wellbore 66'. The lower end of the marine riser isconnected to the blowout preventer stack v110 through a universal joint112 and a sliding joint 114.

One method of connecting the marine riser pipe 106 to the spar buoy hull12, as shown in larger scale and numbered in FIGURE 7, includes a pairof slips 116 set in cavities 118 in the wall 120 of the well 22. Theslips 116 are controlled from the deck of the platform 14 through amanifolding arrangement 122 and a hydraulic line 124, extending to apressure source on the deck 20 through the compartments 27. A pair ofinflatable circular rubber seals 126 are fixed to the inner wall 120 ofthe central well 22, above and below the ship cavities 118. The marineriser pipe 106 can be hung in the well 22 by a pipe string connectedthereto by a releasable connection such as a J-connector joint. When themarine riser pipe 106 has been lowered through the spar buoy hull 12until the upper end thereof is just .above the upper one of the seals126, the fluid line 124 is pressured up, breaking the shear pins 128which hold the slips 116 in the wall 120 and driving the slips 116downwardly into engagement with the marine riser pipe 106. By thenpressuring up the pneumatic seals 126, through a flexible line 130 alsoextending up through the compartments 27 to a pressure source on thedeck of the platform 14, a fiuidtight joint is produced. The heave ofthe drilling vessel 10 is taken up in the sliding joint 114 of the riserpipe 106 and the slight movement of the vessel 10 from directly abovethe borehole 66 is compensated for by a universal joint v112, theflexibility of the riser pipe 106 compensating for other movements suchas roll. A short riser section 132 is shown as being held in the upperend of the well 22 by a pair of slips 134, to direct the drilling mudfrom the upper end of the central well 22 to a central well or moonpoolextending through the platform 14. The riser section 132, which couldalso be suspended by slips mounted in the wall of the moonpool, isnecessarily removable regardless of where it is supported, to provideclearance for the relative movement between the platform 14 and the sparlbuoy hull 12 when converting between a shipshaped vessel and an abovesurface drilling station.

The riser pipe sections 106 and 132 may be made up and stored in thecentral wells of the spar buoy hull 12 and the platform 14,respectively, when the vessel 10 is in the position shown in FIGURE 1 orthe riser pipe sections may be made up from the drilling deck in thesame manner that drill pipe is made up just prior to being used. Theutilization of the spar buoy hull 12 as a portion of the marine riserserves several functions. First, it does not shield the drill string 32therewithin from the photoelectric position indicating system 72 aswould a separate conductor pipe hung from the deck 20 of the platformthrough the central well 22. Second, it lessens the amount of actualriser pipe 106 that is needed, which in turn lowers the weight and costof the entire apparatus.

A problem associated with utilizing some conventional drilling mudsreturning through the central well 22 is they are opaque to light. Inthe advent that light opaque drilling Inuds are used, the photoelectricsensing means 22 can be replaced by an ultrasonic or acoustic system.However, due to the difficulties involved in forming a very narrow sonicbeam, the emitters or oscillators should all be of different frequenciesand the respective receivers attuned to those frequencies. Purelymechanical sensing means could also be used as could capacitance ormagnetic measuring systems.

It is envisioned that the marine drilling vessel 10 will beself-propelled as indicated by a propeller 136 connected to a propellershaft extending out of the rear end of the ship shaped hull 19 of theplatform 14. When the spar buoy hull 12 is in the position shown in FIG-URE 1, its propulsion motors 62 and 64 will have no effect on themovement of the vessel 10 through the body of water 30 and therefore theengines within the platform 14, for driving the propeller 136, must bepowerful enough to transport the entire vessel 10 across the surface 28of the body of water 30 at a reasonable speed. As an auxiliary means ofpropelling the vessel 10, the ones of the propulsion motors 62 and 64that are under water in the position of FIGURE 1 may be pivotaible intoa position in which their propellers face the rear of the vessel 10 andlaid in driving the vessel 10 through the water. Separate rearwardlydirected auxiliary motors (not shown) may also be mounted on the sparbuoy hull 12 for propelling the vessel 10 more quickly through thewater.

The annulus 24 of the spar buoy hull 12 can be used, duringtransportation, to carry fuel for the powerful motors necessary to drivesuch a large vessel 10 across the vast stretches of an ocean. Drillingmud and any other fluids that are necessary at a drilling site can alsobe stored in the compartments 27 of the annulus 24 which may be 400 feetlong, or longer, in an actual vessel. Therefore, the spar buoy hull 12can serve as a tanker as well as a drilling ship and the vessel 10 willbe almost self-suflicient, requiring no barges to erect the unit andonly minimal visits from supply ships. If the space in the annulus 24 ofthe spar buoy hull 12 is not large enough to carry all the fuel,drilling mud, etc., plates can be welded over the well 22, at both endsthereof, and this temporary compartment can also be used for storage intransit.

What is claimed is:

1. A vessel for supporting equipment buoyantly above the surface of abody of water at a marine site comprising: a platform having at leastone horizontal deck for mounting equipment thereon above the surface ofa body of water; a single longitudinally elongated spar buoy hull; meansfor connecting said platform to said spar buoy bull to provideadjustability of said spar buoy hull between a first and a secondposition of said spar buoy hull with respect to said platform, saidfirst position being with the longitudinal dimension of said spar buoyhull substantially parallel to said deck of said platform, and saidsecond position being with said longitudinal dimension of said spar buoyhull substantially perpendicular to said deck of said platform andcentrally located therebeneath, whereby when said vessel is to betransported across a body of water, said vessel floats in a firstposition with said spar buoy hull in said first position, substantiallyparallel to the surface of said body of water, to reduce thehydrodynamic drag of said vessel and whereby when said vessel is locatedat a marine site, said vessel floats is a second position with said sparbuoy hull in said secend position, depending substantially verticallyinto said body of water to form a stable spar buoy marine structurerelatively unaffected by wave action.

2. A vessel for supporting equipment buoyantly above the surface of abody of water at a marine site comprising: a platform having ashipshaped hull and at least one horizontal deck for mounting equipmentthereon above the surface of a body of water; a longitudinally elongatedspar buoy hull; means for connecting said platform to said spar buoyhull to provide adjustability of said sp ar buoy hull between a firstand a second position of said spar buoy hull with respect to saidplatform, said first position being with the deck of said platformparallel to the longitudinal dimension of said spar buoy hull, and saidsecond position being with said deck of said platform substantiallyperpendicular to said longitudinal dimension of said spar buoy hull,whereby when said vessel is to be transported across a body of water,said vessel floats in a first position with said spar buoy hull in saidfirst position, substantially parallel to the surface of said body ofwater, the shipshaped hull of said platform being buoyantly supported inthe body of water with said spar buoy hull forming a single compositeelongated buoyant shipshaped hull to reduce the hydrodynamic drag ofsaid vessel and whereby when said vessel is located at a marine site,said vessel floats in a second position with said spar buoy hull in saidsecond position, depending substantially vertically into said body ofwater to form a. stable marine structure relatively unaffected by waveaction.

3. A vessel for supporting equipment buoyantly above the surface of abody of water at a marine site comprising: a platform having at leastone horizontal deck for mounting equipment thereon above the surface of-'a body of water; a longitudinally elongated spar buoy hull having acentral well extending therethrough; means for connecting said platformto said spar buoy hull to provide adjustability of said spar buoy hullbetween a first and a second position of said spar buoy hull withrespect to said platform, said first position being with thelongitudinal dimension of said spar buoy hull substantially parallel tosaid deck of said platform, and said second position being with saidlongitudinal dimension of said spar buoy hull substantiallyperpendicular to said deck of said platform, whereby when said vessel isto be transported across a body of water, said vessel floats in a firstposition with said spar buoy hull in said first position, substantiallyparallel to the surface of said body of water, to reduce thehydrodynamic drag of said vessel and whereby when said vessel is locatedat a marine site, said vessel floats in a second position with said sparbuoy hull in said second position, depending substantially verticallyinto said body of water to form a stable marine structure relativelyunaffected by wave action.

4. A vessel as recited in claim 3 wherein there is a well extendingthrough said platform, said wells extending through said spar buoy hulland said platform being coaxial when said vessel is in said secondposition whereby a drill string, suspended from a drilling rig mountedon said deck of said platform over said well through said platform,could extend to the marine bottom through both of said wells.

5. A vessel for supporting equipment buoyantly above the surface of abody of water at a marine site comprising: a platform having at leastone horizontal deck for mounting equipment thereon above the surface ofa body of water; :a longitudinally elongated spar buoy hull; means foradjustably connecting said platform to said spar buoy hull; meansassociated with said spar buoy hull for positioning said spar buoy hullbetween a first and a second position of said spar buoy hull withrespect to said platform, said positioning means comprisinglongitudinally spaced watertight compartments forming buoyancy/ ballasttanks in said spar buoy hull whereby the controlled flooding ofsaidbuoyancy/ballast tanks change the position of'said spar buoy hull withrespect to said platform, selectively actuable means, associated withsaid means for adjustably connecting said platform to said spar buoyhull, for rigidly fixing said spar buoy hull with respect to saidplatform whereby said means for rigidly fixing said spar buoy hull withrespect to said platform is actuated to fix said spar buoy hull withrespect to said platform to hold said vessel in said first and secondpositions and is deactivated during the repositioning of said spar buoyhull from one of said first and second positions to the other of saidpositions, said first position being with the longitudinal dimension ofsaid spar buoy hull substantially parallel to said deck of saidplatform, and said second position being with said longitudinaldimension of said spar buoy hull substantially perpendicular to saiddeck of said platform, said buoyancy/ ballast tanks being of a capacitysufiicient to raise said platform above the surface of a body of waterwhen said vessel is in said second position, whereby when said vessel isto be transported across a body of water, said vessel floats in a firstposition with said spar buoy hull in said first position, substantiallyparallel to the surface of said body of water, to reduce thehydrodynamic drag of said vessel and whereby when said vessel is locatedat a marine site, said vessel floats in a second position 'with saidspar buoy hull in said second position, depending substantiallyvertically into said body of water and said platform fully above thesurface of said body of water to form a stable marine structurerelatively unaffected by wave action.

6. A vessel as recited in claim 5 wherein the means for connecting saidspar buoy hull to said platform is a pivotal connection; at least onebrake drum fixed to one relatively rotatable element of said pivotalconnection and at least one brake shoe mounted on the other relativelyrotatable element of said pivotal connection; and means for selectivelyactuating said at least one brake shoe to force said at least one brakeshoe against said at least one brake drum to fix said spar buoy hullwith respect to said platform.

7. A vessel as recited in claim 6 wherein said pivotal connectioncomprises a yoke fixed at one end of said spar buoy hull; means forrotatably journaling said platform between opposing arms of said yoke;brake drums concentrically mounted on said opposing yoke arms adjacentsaid platform; and at least one brake shoe pivotally mounted on saidplatform in conjunction with each of said opposing yoke arms.

8. A vessel as recited in claim '7 wherein there is a pair of coaxiallymounted brake shoes facing opposite sides of each of said brake drums; acable winding reel mounted on a rotatable drive means on said platformand located adjacent each brake drum opposite the coaxial mounting pointfor said pair of brake shoes; and a cable extending between each of saidbrake shoes and said reel 'whereby when said reels are rotated to oneposition the pairs of brake shoes are actuated and press firmly on saidbrake drums and when said reels are rotated to a second position, saidpairs of brake shoes are deactivated and are not firmly pressed againstsaid brake drum.

9. A vessel for supporting equipment buoyantly above the surface of abody of water at a marine site comprising: a platform having at leastone horizontal deck for mounting equipment thereon above the surface ofa body of water; a longitudinally elongated spar buoy hull; means forconnecting said platform to said spar buoy hull to provide adjustabilityof said spar buoy hull between a first and a second position of saidspar buoy hull with respect to said platform, said means for adjustablyconnecting said platform to said spar buoy hull comprises means forrotatably journaling said platform and means for selectively adjustingthe position of said spar 'buoy hull with respect to said platformcomprising meshing gear means for rotating said platform with respect tosaid spar buoy hull, said first position being with the longitudinaldimension of said spar buoy hull substantially parallel to said deck ofsaid platform, and said second position being with said longitudinaldimension of said spar buoy hull substantially perpendicular to saiddeck of said platform, whereby when said vessel is to be transportedacross a body of water, said vessel floats in a first position with saidspar buoy hull in said first position, substantially parallel to thesurface of said body of Water, to reduce the hydrodynamic drag of saidvessel and whereby when said vessel is located at a marine site, saidvessel floats in a second position with said spar buoy hull in saidsecond position, depending substantially vertically into said body ofwater to form a stable marine structure relatively unaffected by waveaction.

10. A vessel as recited in claim 9 wherein said means for rotatablyjournaling said platform comprises a yoke fixed to one end of said sparbuoy hull, said platform being journaled between the arms of said yoke.

11. A vessel as recited in claim 10 wherein said means for journalingsaid platform comprises coaxial cylindrical apertures in the opposingfaces of each of said yoke arms; and a plurality of rotatable bearingsmounted on a plate fixed to said platform opposing each of saidcylindrical apertures, said bearings being spaced around thecircumference of a circle so all of said bearings contact the inner wallof said opposed cylindrical aperture.

12. A vessel as recited in claim 11 wherein a circular internal rack isconcentrically fixed within at least one of said cylindrical apertures;a pinion meshing with said racks, said pinion being mounted on a driveshaft rotatably mounted coaxially with the pivotal axis of saidplatform; .and means for rotating said drive shaft.

13. A vessel for supporting equipment buoyantly above the surface of abody of water at a marine site comprising: a platform having at leastone horizontal deck for mounting equipment thereon above the surface ofa body of water; a longitudinally elongated spar buoy hull; means forconnecting said platform to said spar buoy hull to provide adjustabilityof said spar buoy hull between a first and a second position of saidspar buoy hull with respect to said platform; primary and secondarymeans associated with said spar buoy hull for positioning said spar buoyhull with respect to said platform, said primary means comprisinglongitudinally spaced watertight compartments forming buoyancy/ballasttanks in said spar buoy hull whereby the controlled flooding of saidbuoyancy/ballast tanks change the position of said spar buoy hull withrespect to said platform; a secondary positioning means comprising amechanical connection extending between said platform and said spar buoyhull; and means for actuating said mechanical connection to secondarilyreposition said spar buoy hull with respect to said platform; said firstposition of said spar buoy hull with respect to said platform being withthe longitudinal dimension of said spar buoy hull substantially parallelto said deck of said platform, and said second position being with saidlongitudinal dimension of said spar buoy hull substantiallyperpendicular to said deck of said platform, whereby when said vessel isto be transported across a body of water, said vessel floats in a firstposition with saidspar buoy hull in said first position, substantiallyparallel to the surface of said body of water, to reduce thehydrodynamic drag of said vessel and whereby when said vessel is locatedat a marine site, said vessel floats in a second position with said sparbuoy hull in said second position, depending substantially verticallyinto said body of water to form a stable marine structure relativelyunaffected by wave action.

14. A method of utilizing the vessel of claim 13 at a marine site whensaid vessel is transported to a marine site in said first position,comprising the following steps in the order recited:

(a) flooding said buoyancy/ballast tanks of said spar buoy hull untilsaid spar buoy hull attains a negative buoyancy and is suspended beneathsaid platform, which is buoyantly floating on the surface, whereby saidspar buoy hull moves into substantially said second position;

(b) actuating said secondary positioning means, connected between saidspar buoy hull and said platform, to position finally said spar buoyhull with respect to said platform;

(c) rigidly fixing said spar buoy hull with respect to said platform;and

(d) evacuating said buoyancy/ballast tanks until said spar buoy hull hasenough positive buoyancy to raise the platform a distance above thesurface of said body of water.

15. A means for indicating the position of an object in an observationarea including: a position sensing means extending at least across saidarea under observation, said position sensing means comprisinga firstenergy emitting means located to one side of said observation area fortransmitting parallel beams of energy in a first plane across said areaunder observation; a plurality of first energy receiving meanspositioned across said observation area from said first energy emittingmeans to each receive one of said beams transmitted across saidobservation area from said first energy emitting means; a second energyemitting means located to one side of said observation area fortransmitting parallel beams of energy in a second plane parallel to saidfirst plane across said observation area, said parallel beamstransmitted by said first energy emitting means being nonparallel tosaid parallel beams transmitted by said second energy emitting means; aplurality of second energy receiving means positioned across saidobservation area from said second energy emitting means to each receiveone of said beams transmitted across said observation area from saidsecond energy emitting means; a display means spaced from said positionsensing means, said display means comprising a display area similar inshape to said observation area; a plurality of elongated transparentlight conducting means extending across said display area in a patterncorresponding to the pattern of said energy beams to be transmittedacross said observation area; a light source being associated with eachof said transparent light conducting means; means for directing lightemitted from each of said light sources fully through said respectivelight conducting means; and means for connecting said each of said lightsources with the respective energy receiving means to cause selectedlight sources to be energized forming a light and dark pattern of saidtransparent light conducting means including a pair of contrasting andintersecting transparent light conducting means, the intersection ofwhich indicates the position of the object in said observation area,which has blocked a pair of nonparallel beams of energy.

16. The position indicating means of claim 15 wherein said energyemitting means comprises at least one source of light, and said energyreceiving means comprises photocells.

17. The position indicating means of claim 15 wherein said energyemitting means comprises sources of sonic energy.

18. The position indicating means of claim 16 wherein said means forconnecting said each of said light sources with the respective photocellcomprises a signal amplifying means.

19. The position indicating means of claim 15 wherein said transparentlight conducting means comprises glass rods.

20. The position indicating means of claim 15 wherein said transparentlight conducting means comprises Lucite rods.

21. A vessel for supporting equipment buoyantly above the surface of abody of water at a marine site comprising: a platform having at leastone horizontal deck for mounting equipment thereon above the surface ofa body of Water; a longitudinally elongated spar buoy hull; means forconnecting said platform to said spar buoy hull to provide adjustabilityof said spar buoy hull between a first and a second position of saidspar buoy hull with respect to said platform, said first position beingwith the longitudinal dimension of said spar buoy hull substantiallyparallel to said deck of said platform, and said second position beingwith said longitudinal dimension of said spar buoy hull substantiallyperpendicular to said deck of said platform, said vessel floating insaid second position with said spar buoy hull depending substantiallyvertically into said body of water to form a stable marine structurerelatively unaifected by wave action; selectively actuable propulsionunits arranged on said spar buoy hull, and located beneath the surfaceof said body of water when said spar buoy hull is in said secondposition, said propulsion units being capable of locating dynamicallysaid vessel when said vessel 'is in said second position; transpondersfixedly placed with respect to the marine bottom, each of saidtransponders being keyed to emit a discrete signal transmitted by thebody of water; corresponding transducers located on said marine vesselfor receiving said signals, each of said corresponding transducers beingkeyed to receive the signal emitted by one of said transponders whereinsaid marine vessel can be laterally and radially positioned.

22. Apparatus for indicating the position of a floating vessel, asrecited in claim 4, with respect to a borehole extending into theformations underlying a marine bottom when said vessel is in said secondposition; a drilling rig mounted'on the deck of said platform; a drillstring having means connected to an end thereto to form said borehole insaid marine bottom, said drill string being suspended from said drillingrig and extending through said aligned wells extending through said sparbuoy hull and said platform, the intervening body of water, and intosaid borehole extending into said formations underlying said marinebottom; selectively actuatable propulsion units arranged on said sparbuoy hull so as to be beneath the surface of said body of water whensaid vessel is in said second position, said propulsion units beingcapable of locating dynamically said vessel when said vessel is in saidsecond position; and a position sensing means located in said centralwell of said spar buoy hull for providing an indication of the positionof said drill string in said central well whereby an off-center positionof said drill string in said central well indicates a correspondingdeviation of said vessel from directly above the upper end of saidborehole at said marine bottom.

23. A drilling vessel as recited in claim 22 wherein there is means forselectively actuating said propulsion units in response to the indicateddeviation of said drill string from the axis of said central wellwhereby the drilling vessel is held substantially over said borehole.

24. A drilling vessel as recited in claim 23 wherein there are manualcontrols for selectively actuating said propulsion units, said controlsbeing located on said platform; and display means connected to saidposition indicating means, said display means being located on saidplatform adjacent said manual controls for selectively actuating saidpropulsion units, said display means visually portraying the portion ofsaid drill string in the central well at the axial position of saidposition indicating means.

25. A drilling vessel as recited in claim 24 wherein said positionindicating means is located near the lower end of said central well.

26. A drilling vessel as recited in claim 23 wherein said positionindicating means comprises a photoelectric device.

27. A drilling vessel as recited in claim 23 wherein said positionindicating means comprises an acoustic device.

28. A drilling vessel as recited in claim 26 wherein said positionindicating means comprises: a first light source means located to oneside of said central well for transmitting parallel beams of light in afirst plane across said central well; a plurality of photocellspositioned across said central vwell from said first light source meansto each receive one of said light beams transmitted across said centralwell from said first light source means; a second light source meanslocated to one side of said central well for transmitting parallel lightbeams in a second plane parallel to said first plane across said centralwell, said parallel light beams transmitted by said first light sourcemeans being nonparallel to said parallel light beams transmitted by saidsecond light source means; and a plurality of photocells positionedacross said central Well from said second light source means to eachreceive one of said light beams transmitted across said central wellfrom said second light source means.

29. A drilling vessel as recited in claim 28 wherein said display meanscomprises: a display area similar in shape to a cross section of saidcentral well at the photoelectric device; a plurality of elongatedtransparent light conducting means extending across said display area ina pattern corresponding to the pattern of light beams to be transmittedacross said central well; a plurality of third and fourth light sourcemeans, each of said third and fourth light source means being associatedwith one of said transparent light conducting means for directing thelight from each of said third and fourth light sources fully throughsaid respective light conducting means; and means for connecting each ofsaid third and fourth light source means with said respective first andsecond light source means to cause selected ones of said third andfourth light source means to be energized forming a light and darkpattern of said transparent light conducting means including acontrasting pair of intersecting transparent light conducting means, theintersection of which indicates the position of said drill string insaid central well.

30. A spar buoy drilling vessel comprising a platform supported abovethe surface of a body of water by a spar buoy hull; a central wellextending through said spar buoy hull, said central well forming aportion of a marine conductor connecting a wellhead fixed to said marinebottom and a level within said spar buoy vessel above the surface of thebody of water.

31. A spar buoy drilling vessel as recited in claim 30 wherein there isa removable marine conductor section extending between the lower end ofsaid spar buoy hull and the upper end of said wellhead; and means forreleasably supporting said marine conductor section in said central welland sealing said marine conductor section to said spar buoy hull.

References Cited UNITED STATES PATENTS 3,191,570 6/1965 Henderson 1l41443,273,526 9/1966 Glosten 114-05 3,336,572 8/1967 Paull et al. 166O.5

MILTON BUCHLER, Primary Examiner.

TRYGVE M. BLIX, Assistant Examiner.

